This invention relates to magnetic disk drives and more particularly, to a system for recirculating air in an enclosure for the disk drive.
Magnetic disk drives are extensively used in computer systems.
Large magnetic disk drives have a driven air blower for circulating air across the disks and over the base plate. Examples of such drives are the IBM 3350 supplied by International Business Machines Corporation and STC 8350, supplied by Storage Technology Corporation. Another example is the ISS/UNIVAC 717 disk drive which has vented spacer rings with recirculating air ducted over the top of the spindle. The IBM 2314 disk drive also uses vented spacer rings.
Recently, smaller disk drives have been introduced. An example of such a disk drive is the IBM 3726 which is also known as the IBM System 32. Similar disk drives are made by many companies. These disk drives make use of very lightly loaded magnetic recording heads which are generally referred to as "Winchester" heads. In small magnetic disk drives of this type, there is no forced air circulation from a driven blower or the like. Some air flow is induced by the spinning action of the bottom of the lowermost disk in the pack and fins on the bottom of the hub. There is air flow beneath the bottom of the hub and across this lower surface. This air is channeled through a recirculating filter, under the base plate which serves as its heat exchanger, and back under the hub, completing the air path.
The cooling of prior art magnetic disk drives has not been completely satisfactory. The rotary assembly, including spindles, disks and spacer rings, are mounted on a precisely machined cast aluminum base plate, together with the magnetic recording head actuator assembly. As these machines warm up, a thermal gradient in the base plate is generated due to heat being extracted from the bottom side of the base plate. Magnetic recording head alignment changes due to base plate warpage as the base plate thermal gradient changes. For this reason, prior art machines require a warm-up period for the thermal gradients to stabilize and thus for the magnetic recording head alignment to stabilize before read/write functions can be exercised.
An object of this invention is to provide a machine with circulating air flowing over both the top and the bottom of the base plate to reduce thermal gradients in the base plate so that the disk drive is ready for operation as soon as it is started.
It is a further object of the present invention to provide a disk drive in which air is driven through a closed path in the drive by the rotating action of the magnetic disks which pump air through this closed path.
It is another object of the present invention to minimize thermal gradients in magnetic disks.
It is another object of the present invention to provide heat transfer from the head disk enclosure remote from the base plate.
It is another object of the present invention to provide increased air flow through the head disk assembly.